Massinissa Hadjloum

Via-Hole Less Broadband Grounded Coplanar to Coupled Microstrip Transition for up to 40 GHz

A broadband via-hole less transition from a conductor-backed coplanar waveguide (CBCPW) to a parallel coupled microstrip line (CMS) via microstrip section (MS) is reported in this paper that is realized on a MCL FX-2 substrate (100 μm thick). This transition should find a wide variety of applications due to its demonstrated broadband (from 4.5 GHz up to 39.5 GHz) behavior, ease of fabrication, and low manufacturing cost. In addition, utilization of the MS section between the CBCPW and CMS sections allows putting ground electrode in a different plane than the signal electrodes. This exibility made possible by electromagnetic field coupling between the bottom and top ground planes simplifies the transition manufacturing and facilitates the characterization of optical components driven with CMS line using coplanar probes.

An ultra-wideband dielectric material characterization method using grounded coplanar waveguide and genetic algorithm optimization

An ultra-wideband complex permittivity extraction method is reported here using numerical fitting of scattering parameters to measured results. A grounded coplanar waveguide transmission line is realized on an unknown dielectric material, whose dielectric constant and loss tangent are extracted by the best fitting of the simulated magnitude, |S21|, and phase, ϕ21, of forward scattering parameter using an electromagnetic full-wave simulator (high frequency structure simulator) to the measured results. The genetic algorithm is employed for optimum rapid extraction, where errors between the numerically simulated and measured S21 (|S21| and ϕ21) are minimized in an iterative manner. As long as the convergence criterion is not satisfied, modifications to dielectric properties are made with this genetic algorithm implemented in Matlab. Feasibility of this extraction technique is validated on benzocyclobutane polymer from 10u2009MHz to 40u2009GHz.

Leaky waveguide deflector for 40 GS/s and 6 bits all-optical analog-to-digital converters

Abstract Analog-to-digital converters (ADC) are an important part of realizing direct digital receivers in future communication systems, where broad bandwidth, high effective number of bits, and low DC power consumption are an important requirement of achieving it at microwave frequencies. Due to a number of physical limitations of electrical ADC, design of an all-optical analog-to-digital converter (AOADC) is pursued and presented here based on highly stable mode-locked laser based clock signal pulses for optical sampling, and a combination of leaky waveguide optical deflector using electro-optical (EO) polymers and stationary optical windows followed with high-speed photodetectors as optical quantizer. The reported principle of the AOADC is to convert a broadband RF signal into a spatially sampled light using optical deflection angle variation before quantizing it using either binary or Gray coded optical windows. The design and modeling of an AOADC working up to 20 GHz RF frequencies (with Nyquist sampling rate of over 40 GS/s) and for providing a resolution of better than 6 bits with under 4W of power consumption. Performance is currently limited by both optical and microwave attenuation in the available EO polymers.

Conductor-backed coplanar waveguide to microstrip transition on BCB polymer thin film with bandwidth over 60 GHz

A conductor-backed coplanar waveguide to microstrip via-hole less transition realized on a commercial BCB (Benzocyclobutene) polymer thin film is studied in this paper. By using thin substrates with a low-permittivity, the achieved experimental bandwidth covers the frequency band from 1 GHz to 69 GHz. This transition, using electromagnetic coupling between the bottom and top ground planes, is very useful and requested in component packaging, on-wafer measurements of microstrip based monolithic microwave integrated circuit and for interconnections in hybrid circuits including both microstrip and coplanar structures.

Ultra-wideband GCPW-CMS-GCPW transition for characterization of all-optical ADCs based on leaky waveguide deflector

Design of an all-optical analog-to-digital converter (AOADC) is presented here based on a leaky waveguide deflector in electro-optic (EO) polymers driven by a coupled microstrip (CMS) line. In particular, back-to-back transitions from grounded coplanar (GCPW) to microstrip line (MS) and from microstrip to CMS line, permitting to connectorize and characterize the EO deflector, are presented. The best achieved bandwidth is over 53 GHz with a remarkably lower cutoff frequency of only 2 GHz. This transition, without via-hole, using electromagnetic coupling between the bottom and top ground planes simplifies the manufacturing and facilitates the characterization of component by means of coplanar probes.

Improvement of both bandwidth and driving voltage of polymer phase modulators using buried in-plane coupled micro-strip driving electrodes

A large performance improvement of polymer phase modulators is reported by using buried in-plane coupled microstrip (CMS) driving electrodes, instead of standard vertical Micro-Strip electrodes. The in-plane CMS driving electrodes have both low radio frequency (RF) losses and high overlap integral between optical and RF waves compared to the vertical designs. Since the optical waveguide and CMS electrodes are located in the same plane, optical injection and microwave driving access cannot be separated perpendicularly without intersection between them. A via-less transition between grounded coplanar waveguide access and CMS driving electrodes is introduced in order to provide broadband excitation of optical phase modulators and avoid the intersection of the optical core and the electrical probe. Simulation and measurement results of the benzocyclobutene polymer as a cladding material and the PMMI-CPO1 polymer as an optical core with an electro-optic coefficient of 70u2009pm/V demonstrate a broadband operation ...

Sensitivity improvement of broadband electro-optic polymer-based optical phase modulator using 1D and 2D photonic crystal structures

This Letter introduces the design and simulation of a microstrip-line-based electro-optic (EO) polymer optical nphase modulator (PM) that is further enhanced by the addition of photonic crystal (PhC) structures that are in nclose proximity to the optical core. The slow-wave PhC structure is designed for two different material configurations nand placed in the modulator as a superstrate to the optical core; simulation results are depicted for both n1D and 2D PhC structures. The PM characteristics are modeled using a combination of the finite element nmethod and the optical beam propagation method in both the RF and optical domains, respectively. nThe phase-shift simulation results show a factor of 1.7 increase in an effective EO coefficient (120 pm/V) while nmaintaining a broadband bandwidth of 40 GHz.

Study of an Electro-Optic leaky waveguide deflector for application in All-Optical Analog-to-Digital Converters

High speed Analog-to-Digital Converters (ADCs) are key components for enhancing high-speed communication systems, such as broadband satellites at millimeter wave frequencies and extremely high-throughput wireless systems. Tens of gigahertz ADCs are required to cope with the increasing need of real-time digital signal processing of broad bandwidth analog RF signal in direct digital receivers. Electronic ADCs have inherent limitations for reaching high bandwidth with an appropriate resolution due to the high timing jitters of electronics clocks, state of art values over 100 fs for [4]. We are studying an All-Optical Analog-to-Digital Converter (AOADC) based on an Electro-Optic (EO) polymer deflector for achieving higher than 20 GHz of bandwidth with a 6 bits of resolution, taking advantage of much lower timing jitters of modes-locked lasers on one hand and very good materials qualities of EO polymers on the other hand (excellent velocity matching between the microwave signals and optical waves in polymeric materials and EO coefficient up to 350 pm/V versus 31 pm/V of the popular inorganic crystal LiNbO3). The EO deflector converts magnitude variation of the analog RF voltage, applied on its Coupled Mirco-Strip (CMS) driving electrodes, into variations of deflection angle of an optical leaky beam out of the optical deflector using the linear EO effect (Pockels effect). This variation of deflection angle as result of the applied RF signal is then quantized using optical windows followed by an array of high-speed photodetectors. This paper reports design optimization of an EO deflector based on polymer materials. On the one hand, the leaky optical waveguide is optimized for achieving up to 6.3 bits of resolution, on the other hand, a transition from coplanar waveguide pads (CPW) to the CMS line is designed for RF characterization of optical deflectors by means of Ground-Signal-Ground (GSG) probes. Experimental validation of 2 cm long of via-free CPW-CMS transition built on a 40 μm thick Benzo Cyclo Butene (BCB) polymer shows a bandwidth higher than 25 GHz. This transition is very helpful for packaging and connectorization of photonic-microwave devices.

Design and realization of high-performance microwave and millimeter wave band-pass filters on thin polymer films

During the last decade, we observed an explosion of wireless communications and multimedia services. The rapid growth of data exchanged, through information and communication networks, requires the development of components and devices with higher performance and improved functionality, while satisfying the constraints of weight, size, power consumption and cost. Microwave filters are essential components in various electronic systems, including cellular radio, radars and satellite communications. They are indispensable to detect weak signal buried in noise and improve radars sensitivity. They are also very useful to improve spectrum efficiency in software radio technology. In microwave communication systems, band-pass filters are usually used in both receivers and transmitters. So they are requested to meet the following electronic requirements: low insertion loss, high frequency selectivity, phase linearity and no harmonic response. Band-pass filters structures are widely reported in the literature. However these studies were conducted in the most cases on thick commercial substrates [1-3]. To date, very few studies have focused on filters on thin films whereas the low thickness of the substrate facilitates the coupling between the circuits on the surface and the lower ground plane [4] which allows having a high selectivity filter. This paper reports the design and manufacturing of microstrip band-pass filters with good performance in terms of both insertion loss and selectivity.The proof of concept is carried out on thin BCB polymer (70 μm) film very used in microelectronics thanks to its low loss tangent (tan δ = 0.0025). The studied filters are constituted of two resonators and they combine the compactness of microstrip resonators and the connection facility of coplanar pads due to microstrip-grounded coplanar waveguide transitions integrated with the filters. The filters structures, that will be presented,have the following performance:. 6% bandwidth and -1.6 dB insertion losses at central frequency of 15 GHz, 4.5% bandwidth and -1.7 dB insertion losses at central frequency of 20 GHz, 5.5% bandwidth and -1.5 dB insertion loss at central frequency of 25 GHz, 8% bandwidth and -1.1 dB insertion loss atcentral frequency of 35 GHz, 4.8% bandwidth and -1.4 dB insertion losses at central frequency of 45 GHz. The filters on thin polymer film have the advantage of being low cost and very easy to fabricate.

Coplanar waveguide to microstrip transition in thin polymer film for characterization and packaging of microwave photonic components

We report in this paper two types of broadband transitions between microstrip and coplanar lines on thin benzocyclobutene (BCB) polymer substrate. They are both via-free, using electromagnetic coupling between the bottom and top ground planes, which simplifies the manufacturing of components driven by microstrip electrodes. In the first ones, the bottom ground is not patterned, which makes them particularly suitable to on-wafer measurement of components under development with coplanar probes. An ultra-broad bandwidth of 68 GHz (from 1 GHz to 69 GHz) was achieved with 20-pm BCB. In the second ones, intended for connectorizing components on thin substrate with coplanar connectors, the bottom ground is patterned to match the narrow center conductor (54 μm) on thin substrate to the wide center conductor (127 μm) of the connector with a tapered section, achieving to a experimental bandwidth 13 GHz for the moment.